Traveler’s Backpack is a handy tool that adds about 45 extra inventory slots including tanks to hold liquids. All you need to do is craft it and either place it on the ground and hold shift while right-clicking it with an empty hand or hold the backpack in your hand, hit B and then press the button in the bottom left to wear it.
And simply press B while wearing it to open the inventory up.
It functions as a portable bed as well since it has a sleeping bag built in. Just set the backpack down, right-click it and click the sleeping bag button that’s now in the bottom left corner.
It has 2 tool slots that can be cycled easily with whatever tool is active in your inventory. Simply hold z and scroll with your mouse to swap between tools in your backpack.
There’s also a crafting table within the backpack. Hit B again to open the pack and the 9 brown squares are the crafting grid!
While you can drop liquids from buckets directing into the tank slots, this mod also has a hose attachment that can suck up the liquids:
You can drink from the hose as well:
Or put out fires! All you need to do is hold N and scroll with your mouse to toggle between the 3 hose options.